An air supply device for a pneumatic spring arrangement in a vehicle is described in EP 1 901 934 B1. This pneumatic spring arrangement has inlet and outlet air lines that are separate from one another. An air filter is arranged in the inlet air line and a silencer in the outlet air line.
A similar air supply device with a compressor and a silencer is shown in DE 101 21 582 C2 and EP 1 306 239 B1.
DE 102 23 405 84, DE 103 01 119 A1, EP 1 608 521 B1 and DE 10 2004 057 575 A1 show a pneumatic spring system or else an automatic level control for a vehicle, wherein the inlet air and the outlet air is conducted via a joint line. However, a joint line for intake air and discharge air has the disadvantage that air gives off moisture when discharged, which accumulates in the joint line. This moisture is then drawn in again.
Consequently, the air for compressed air generation is frequently drawn in at a place in the vehicle that differs from the place where the air is discharged (venting). This means that the inlet air and the outlet air must be conveyed to the compressor assembly or to the pneumatic spring system in separate lines. The reasons for using different locations are varied. When air is drawn in from the passenger space, for example, the inlet air is already comparatively dry, which reduces the drying required following compression. It has also proved favorable, however, for the inlet air to be removed right behind the vehicle radiator, for example. By contrast, the outlet air may be discharged anywhere on the vehicle. This often happens in direct proximity to the compressor assembly or the pneumatic spring.